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Practice Class 10 Science Chapter 3 – Metals and Non-metals with 5 original NCERT-based MCQs covering reactions with water, metal oxides, amphoteric oxides, ionic compounds and chemical properties, with detailed solutions.
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Chapter Information
Subject: Science
Class: 10
Chapter: Metals and Non-metals
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 2
Difficulty Level: Moderate
Based On: NCERT Syllabus
Introduction
Metals show different chemical properties depending on their reactivity and the substances with which they react. Some metals react vigorously with water, while others react slowly or do not react with water under ordinary conditions.
Metal oxides also show different chemical behaviours. Most are basic, but certain oxides react with both acids and bases. Understanding these reactions helps students explain the behaviour of metals and their compounds.
This Practice Set 2 focuses on reactions with water, amphoteric oxides, ionic compounds and the chemical properties of metals.
What You Will Learn
- Reactions of metals with water
- Formation of metal hydroxides and hydrogen gas
- Amphoteric metal oxides
- Formation of ionic compounds
- Properties of ionic compounds
- Interpretation of chemical equations
- Important concepts for Class 10 Science examinations
Why This Topic Is Important
Questions about reactions with water, the behaviour of metal oxides and ionic compounds help students understand the chemical properties of metals and non-metals.
These concepts are useful for answering multiple-choice questions, interpreting chemical equations and explaining observations from chemical reactions.
5 MCQs with Answers and Detailed Solutions
Q1. Which gas is generally released when sodium reacts with water?
A) Oxygen
B) Hydrogen
C) Carbon dioxide
D) Nitrogen
Answer: Hydrogen
Detailed Solution
Sodium reacts vigorously with water to form sodium hydroxide and hydrogen gas.
The balanced chemical equation is:
$$2Na + 2H_2O \rightarrow 2NaOH + H_2$$
Sodium hydroxide is formed in the solution, while hydrogen gas is released.
The reaction also produces considerable heat. Sodium reacts so vigorously with water that this reaction should not be attempted as an ordinary classroom experiment.
Therefore, hydrogen is the correct answer.
Exam Tip
Remember the general reaction of a sufficiently reactive metal with water:
Metal + Water → Metal hydroxide + Hydrogen
The actual products and reaction conditions depend on the metal.
Q2. Which of the following is an amphoteric oxide?
A) $$Na_2O$$
B) $$MgO$$
C) $$Al_2O_3$$
D) $$CO_2$$
Answer: $$Al_2O_3$$
Detailed Solution
An amphoteric oxide reacts with both acids and bases to form salt and water under suitable conditions.
Aluminium oxide, represented by $$Al_2O_3$$, is an amphoteric oxide.
For example, it reacts with hydrochloric acid:
$$Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O$$
It also reacts with a strong base such as sodium hydroxide under suitable conditions.
Sodium oxide and magnesium oxide are generally classified as basic oxides, whereas carbon dioxide is an acidic oxide.
Therefore, aluminium oxide is the correct answer.
Exam Tip
Remember two important amphoteric oxides:
- Aluminium oxide: $$Al_2O_3$$
- Zinc oxide: $$ZnO$$
Both can react with acids as well as bases.
Q3. Why do ionic compounds generally have high melting points?
A) Their particles are held together by strong electrostatic forces of attraction.
B) They contain only neutral atoms.
C) Their particles have no forces between them.
D) They always exist as gases at room temperature.
Answer: Their particles are held together by strong electrostatic forces of attraction.
Detailed Solution
Ionic compounds contain positively and negatively charged ions. These oppositely charged ions attract each other through strong electrostatic forces.
A considerable amount of energy is required to overcome these forces sufficiently for the solid to melt. Therefore, ionic compounds generally have high melting points.
For example, sodium chloride contains sodium ions and chloride ions arranged in a regular ionic structure.
Hence, strong electrostatic attraction between oppositely charged ions explains the generally high melting points of ionic compounds.
Exam Tip
Do not confuse the melting point of an ionic compound with its electrical conductivity. These are different properties and have different explanations.
Q4. Which statement about the electrical conductivity of solid sodium chloride is correct?
A) Solid sodium chloride conducts electricity very well.
B) Solid sodium chloride does not conduct electricity under ordinary conditions because its ions cannot move freely.
C) Solid sodium chloride conducts electricity because it contains free electrons like a metal.
D) Solid sodium chloride conducts electricity only because it contains hydrogen ions.
Answer: Solid sodium chloride does not conduct electricity under ordinary conditions because its ions cannot move freely.
Detailed Solution
In solid sodium chloride, the positive and negative ions occupy fixed positions in the ionic lattice. These ions cannot move freely through the solid, so solid sodium chloride does not conduct electricity under ordinary conditions.
When sodium chloride is molten or dissolved in water, its ions become mobile and can carry electric charge.
Therefore, solid sodium chloride does not conduct electricity under ordinary conditions because its ions are not free to move.
Exam Tip
Remember the distinction:
- Solid ionic compound: Ions are fixed in position.
- Molten ionic compound: Ions can move.
- Aqueous ionic solution: Mobile ions can carry electric current.
Q5. Which statement correctly describes the reaction of calcium with water?
A) Calcium reacts with water to form calcium hydroxide and hydrogen gas.
B) Calcium reacts with water to form calcium chloride and oxygen gas.
C) Calcium does not react with water under any conditions.
D) Calcium reacts with water to form calcium oxide and nitrogen gas.
Answer: Calcium reacts with water to form calcium hydroxide and hydrogen gas.
Detailed Solution
Calcium reacts with water to form calcium hydroxide and hydrogen gas.
The balanced chemical equation is:
$$Ca + 2H_2O \rightarrow Ca(OH)_2 + H_2$$
Calcium reacts less vigorously with cold water than sodium does. The calcium hydroxide produced is only sparingly soluble in water.
This reaction illustrates how some reactive metals form metal hydroxides and release hydrogen when they react with water.
Therefore, Option A is correct.
Exam Tip
Learn the difference between the reactions of sodium and calcium with water. Both produce hydrogen, but their reaction rates and vigour differ.
Important Concepts
Reaction of Metals with Water
Different metals react with water at different rates.
Highly reactive metals such as sodium react vigorously with cold water. Calcium also reacts with cold water, but less vigorously than sodium.
The products of these reactions commonly include a metal hydroxide and hydrogen gas.
Example:
$$2Na + 2H_2O \rightarrow 2NaOH + H_2$$
Metal Oxides
Many metals react with oxygen to form metal oxides. Most metal oxides are basic, but some exhibit amphoteric behaviour.
Amphoteric Oxides
Amphoteric oxides react with both acids and bases under suitable conditions.
Important examples include:
- Aluminium oxide: $$Al_2O_3$$
- Zinc oxide: $$ZnO$$
Ionic Compounds
Ionic compounds consist of positively charged and negatively charged ions held together by electrostatic attraction.
They generally have high melting and boiling points because strong forces must be overcome to separate their ions.
Electrical Conductivity of Ionic Compounds
Ionic compounds generally do not conduct electricity in the solid state because their ions cannot move freely.
When molten or dissolved in water, their mobile ions can carry electric current, provided the compound is sufficiently soluble in water.
Related Practice Questions
Q1. Write the balanced chemical equation for the reaction of calcium with water.
Q2. What is an amphoteric oxide? Give two examples.
Q3. Why do ionic compounds generally have high melting points?
Q4. Why does molten sodium chloride conduct electricity while solid sodium chloride does not?
Q5. How does the reaction of sodium with water differ from the reaction of calcium with water?
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Which product is formed when sodium reacts with water?
A) Sodium hydroxide
B) Sodium chloride
C) Sodium carbonate
D) Sodium sulphate
Q2. Which of the following is an amphoteric oxide?
A) $$CO_2$$
B) $$SO_2$$
C) $$ZnO$$
D) $$Na_2O$$
Q3. Why can molten ionic compounds conduct electricity?
A) Their ions are mobile.
B) Their ions are fixed in place.
C) They contain only neutral molecules.
D) They have no charged particles.
Q4. Which substance is produced when calcium reacts with water?
A) Calcium chloride
B) Calcium hydroxide
C) Calcium carbonate
D) Calcium sulphate
Q5. What holds the ions together in an ionic compound?
A) Weak magnetic attraction only
B) Strong electrostatic attraction between oppositely charged ions
C) A force between neutral gases only
D) No attractive force
Exam Tips
- Learn the products formed when reactive metals react with water.
- Practise writing balanced chemical equations.
- Remember the examples of amphoteric oxides.
- Understand why ionic compounds generally have high melting points.
- Distinguish between the conductivity of solid and molten ionic compounds.
- Compare the vigour of reactions of different metals with water.
- Avoid treating every metal as equally reactive.
Quick Revision Notes
- Sodium reacts vigorously with water.
- Sodium and water produce sodium hydroxide and hydrogen gas.
- Calcium reacts with water to form calcium hydroxide and hydrogen gas.
- Aluminium oxide and zinc oxide are amphoteric oxides.
- Ionic compounds contain oppositely charged ions.
- Strong electrostatic attraction contributes to the high melting points of ionic compounds.
- Solid ionic compounds generally do not conduct electricity because their ions are fixed.
- Molten ionic compounds can conduct electricity because their ions are mobile.
Common Mistakes Students Make
- Confusing hydrogen gas with oxygen gas in reactions of metals with water.
- Forgetting to balance chemical equations.
- Assuming all metal oxides are basic.
- Confusing amphoteric oxides with acidic oxides.
- Assuming solid ionic compounds conduct electricity in the same way as metals.
- Forgetting that ionic compounds can conduct electricity when molten.
- Assuming sodium and calcium react with water with equal vigour.
Key Takeaways
- The reactions of metals with water depend on their reactivity.
- Sodium reacts vigorously with water, while calcium reacts less vigorously.
- Amphoteric oxides react with both acids and bases under suitable conditions.
- Ionic compounds consist of oppositely charged ions.
- Strong electrostatic attraction explains their generally high melting points.
- Mobile ions allow molten ionic compounds and suitable aqueous solutions to conduct electricity.
FAQs
Q. What happens when sodium reacts with water?
Answer:
Sodium reacts vigorously with water to form sodium hydroxide and hydrogen gas.
$$2Na + 2H_2O \rightarrow 2NaOH + H_2$$
Q. What are amphoteric oxides?
Answer:
Amphoteric oxides react with both acids and bases under suitable conditions. Aluminium oxide and zinc oxide are examples.
Q. Why do ionic compounds have high melting points?
Answer:
Strong electrostatic forces attract oppositely charged ions. Considerable energy is required to overcome these forces sufficiently for melting.
Q. Does solid sodium chloride conduct electricity?
Answer:
Solid sodium chloride does not conduct electricity under ordinary conditions because its ions cannot move freely. Molten sodium chloride can conduct electricity because its ions are mobile.
Q. What happens when calcium reacts with water?
Answer:
Calcium reacts with water to form calcium hydroxide and hydrogen gas.
$$Ca + 2H_2O \rightarrow Ca(OH)_2 + H_2$$
Conclusion
Class 10 Science Chapter 3 – Metals and Non-metals covers reactions of metals with water, amphoteric oxides and the properties of ionic compounds. These original practice questions help students revise important chemical concepts and understand how to interpret chemical equations.
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